My pixel phone has meager storage. Could I use an old phone with bountiful SD space to serve up media via Bluetooth?

Any ideas if this would work practically speaking?

Edit: Looking for a functional equivalent of on-device storage space, i.e., for offline media consumption

USB phone jack is often used for power, so it's unlikely available for OTG storage

Battery life in the server phone should be ok since it will be running in airplane mode with only Wi-Fi and/or Bluetooth, and display off mostly